I ask this here since I have spend to long to find any way to contact GOG with a support mail.

And I fail to see that GOG is allowed to force their customers to buy when using a discount code if they want to use the discount code and not showing what the discount actually is.

If you redeem a discount code to see the discount, you have to buy that game if you want the discount, if you need just 1 or 2 Euros more to pay and don't have it you can't wait a day because the code is already used.

Most countries loot boxes is not allowed, so why is this any different than a loot box ?

I don't like that you can't see discounts in the mail, but you do not have to commit to see discounts on redeem page. Moreover, you're not paying anything for the code, it's not a random thing you get after paying for it, so there's no loot box mechanism.

Loot Box is when you can't see what you get, and that is exactly the same as with how much the discount actually is.

It's inconvenient to see. But it's not random, it's not hidden, you're not paying for it.

The issue with loot box and the reason why some countries consider regulating them is that they are basically (or at least very close to) gambling, as in you pay money to get something random that may or may not be worth what you are paying for it. With all the risk associated with gambling.

Here it's totally different, you don't pay for anything, you can purchase the game for their regular prices and get exactly what you are expecting, it's just some extra discount that you don't know the value of until you "redeem" it.

Also, it's not true that you have to use the discount right away, you can enter the code, see exactly what it offers and click cancel, after which you can reuse it later until the time runs out.

You can just cancel the process before going to the checkout and won't lose the discount. Screenshot attached.

It's so far from a loot box. You can't always see it in the email, sure, but that's literally only a marketing tactic. It takes you two seconds to check whether the code is for something you want when you visit the site. It doesn't kill you to check it on the site.